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A multitude of phenomena—such as the chemical enrichment of the Universe, the mass spectrum of planetary nebulae, white dwarfs and gravitational wave progenitors, the frequency distribution of supernovae, the fate of exoplanets, etc.—are highly regulated by the amounts of mass that stars expel through a powerful wind. For more than half a century, these winds of cool aging stars have been interpreted within the common interpretive framework of 1D models. I here discuss how that framework now appears to be highly problematic.
These stellar winds harbor 3D complexities that bridge 23 orders of magnitude in scale, ranging from the nanometer up to thousands of astronomical units. We need to embrace and understand these 3D spatial realities if we aim to quantify mass loss and assess its effect on stellar evolution. We therefore need to gauge the following:
Only then will it be possible to drastically improve our predictive power of the evolutionary path in 4D (classical) spacetime of any star.
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Download the Supplemental Material (PDF). Includes the Supplemental Text and Supplemental Tables 1-2.
Supplemental Video 1: 3D hydrochemical simulation for a binary system containing a mass-losing asymptotic giant branch (AGB) star, showing (a) the total density; (b) CO/H2 number density; and (c) temperature for a binary system model in which the AGB star has a mass of 1 M⊙, effective temperature of 2,900 K, a radius of 0.9 AU, and a pulsation period of 1 year. The companion has a mass of 0.5 M⊙ and resides at a circular orbit with separation of 10 AU. The simulation time runs for 59.3 years. Owing to dust formation occurring in the region where the temperature is lower than 1,500 K, a wind is initiated with mass-loss rate of 4.7 x 10-6 M⊙ year-1. The formation of two types of spiral structures can readily be seen, one structure being caused by the gravity wake near the companion, the other one caused by the reflex motion of the AGB star. Both spiral structures merge at larger distances from the AGB star. The small ripples in the close vicinity of the AGB star are relics of the pulsation pattern. The same setup for the AGB star not having a companion yields a mass-loss rate of 7.6 x 10-7 M⊙ year-1 (J. Bolte, L. Decin, W. Homan, F. De Ceuster, J. Yates, et al., in preparation). For a simulation time of 59.3 years, the hydrodynamical quantities are then displayed for viewing angles of the system ranging between 0 deg (edge-on view) and 90 deg (face-on view). Also shown is the corresponding CO v = 0 J = 1--0 emission map and line profile at t = 59.3 years for three different viewing angles [at 90 deg (d), at 45 deg (e), and at 0 deg (f)] in the observer's frame calculated using the MAGRITTE 3D radiative transfer solver (De Ceuster et al. 2020a,b}. The video slices through the velocity channel map between -20 and +20 km s-1.